Set a featured image via an advanced file field 2.0 and Save as post type processor in Caldera Forms.

cf_custom_featured_cf2.php

<?php
/**
* Plugin Name: CF featured image
* Author: New0
* Description: Use an advanced File Field 2.0 to save a file as a featured image in a post created via the Save as Post Type processor.
*
*/
//Get File and Post ID before setting the featured image
add_action('caldera_forms_submit_complete', function($form, $referrer, $process_id, $entry_id){
	
  //SET CORRESPONDING FORM AND FIELD ID
  $form_id = "CF5e32b6d71e30b";
  $field_id = "fld_1234802";
	
	if($form['ID'] !== $form_id){
		return;
	}
	//Get submission data
	$submission = Caldera_Forms::get_entry( $entry_id, $form);
	//Get File
	if(is_array($submission['data'][$field_id ])){
		$file = $submission['data'][$field_id ]['value'][0];
	}
	//Get Post ID
	if(is_array($submission['meta']['post_type']['data'])){
		$fp = $submission['meta']['post_type']['data'];
		if(is_array($fp)){
			$fp_data = reset($fp);
			if(is_array($fp_data)){
				$post_id = $fp_data['entry']['ID']['meta_value'];
			}
		}
		
	}
	//Set featured image
	if(isset($post_id) && isset($file)){
		$attachment_id = custom_featured_file( $file, $entry_id );
		$featured = set_post_thumbnail( $post_id, $attachment_id );
	}
	
}, 99, 4);

//Convert the file in attachment and get attachment ID
function custom_featured_file( $file, $entry_id ){
	// Make sure that this file is included, as wp_generate_attachment_metadata() depends on it.
	require_once( ABSPATH . 'wp-admin/includes/image.php' );
		
	// Check the type of file. We'll use this as the 'post_mime_type'.
	$filetype = wp_check_filetype( basename( $file ), null );

	// Get the path to the upload directory.
	$wp_upload_dir = wp_upload_dir();

	$filename = $wp_upload_dir['path'] . '/' . basename( $file );
	$attachment = array(
		'guid'           => $wp_upload_dir['url'] . '/' . basename( $file ),
		'post_mime_type' => $filetype['type'],
		'post_title'     => preg_replace( '/\.[^.]+$/', '', basename( $file ) ),
		'post_content'   => '',
		'post_status'    => 'inherit'
	);

	// Insert the attachment.
	$attach_id = wp_insert_attachment( $attachment, $filename, $entry_id );

	// Generate the metadata for the attachment, and update the database record.
	$attach_data = wp_generate_attachment_metadata( $attach_id, $filename );
	wp_update_attachment_metadata( $attach_id, $attach_data );

	return $attach_id;
}